Vet reports illnesses spread by mosquitoes

Published 5:00 am Thursday, September 29, 2005

One case each of eastern equine encephalitis and West Nile viruswere confirmed Tuesday in Lawrence County, a veterinarian said.

Dr. Mark Herbert, of the Animal Health Center, said tests wereconducted on two horses last week. Tests on one horse came backpositive for eastern equine encephalitis, or EEE, while tests on asecond horse revealed a positive result for West Nile, he said.

There is no cure for the two mosquito-borne diseases, Herbertsaid, but vaccinations that can prevent horses from contracting thedisease are available at any veterinarians’ offices.

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The vaccine takes one to two weeks to become 100 percenteffective, he said, but it is not too late to vaccinate horsesagainst the diseases.

“The season normally ends around Thanksgiving” formosquito-borne viruses, he said.

Cases of West Nile are no longer rare since the disease invadedthe state a few years ago. It can now be found in every state butremains more common in wet states, where mosquitoes thrive.

EEE has been around much longer, but cases have been rare in thepast decade.

Herbert said he last treated a case of EEE two years ago.However, the veterinarian said EEE seems to be staging a smallcomeback.

“In the state overall this year it seems EEE is more prevalentthan it has been in the past,” he said.

Both viruses are transferable to humans by mosquitoes. Cases ofEEE in humans are rare, with an average of four cases per year -primarily in Florida, Georgia, Massachusetts and New Jersey. Thefatality rate of EEE in humans is 35 percent, making it one of themost deadly mosquito-borne diseases in the U.S. It is alsoestimated that 35 percent of people who survive EEE will have mildto severe neurologic damage.

Cases of West Nile still pose a major health risk toMississippians. The Mississippi Department of Health has reported atotal of 43 human West Nile cases and four deaths resulting fromcomplications of the virus so far this year.

September and October are considered the peak months for bothEEE and West Nile. MDH officials continue to urge people to takeprecautions to reduce their exposure to mosquito bites.

The following simple precautions can reduce the risk ofcontracting mosquito-borne viruses: remove sources of standingwater; avoid mosquito-prone areas, especially at night whenmosquito activity is highest; wear protective clothing; and usemosquito repellents that contain DEET, the chemical picaridin oroil of lemon eucalyptus.

Symptoms of West Nile virus infection are often mild or flu-likeand may include fever, headache, nausea, vomiting, a rash, muscleweakness or swollen lymph nodes. In a small number of people,infection can result in encephalitis or meningitis which can leadto paralysis, coma and possibly death.

Symptoms of EEE infection are similar, ranging from a mildflu-like illness to inflammation of the brain, coma and death.

For more information on West Nile and other mosquito-borneviruses call the West Nile hot line at 1-877-WST-NILE or visit theMDH Web site at